DE69711616T2 - PERMANENT, HYDRAULIC-STRETCHED FABRICS - Google Patents

Description

FIELD OF INVENTION

This invention relates to spunlaced nonwoven fabrics and, more particularly, to spunlaced nonwoven fabrics suitable for durable uses and reuses.

BACKGROUND OF THE INVENTION

E.I. du Pont de Nemours and Company (DuPont) has been manufacturing and selling Sontara® spunlaced nonwovens for a number of years. Such spunlaced nonwovens have a wide variety of applications, such as medical gowns and towels, absorbent wipes, and durable articles such as window blinds and apparel interlinings. Sontara® spunlaced nonwovens have been successfully marketed because of their low cost of use and valuable properties such as texture, softness, comfort, drapability, and absorbency.

Spunlaced nonwovens are made by interweaving batts of fibers with high energy water jets, as is basically described in U.S. Patent No. 3,485,706 to Evans et al. The batts can be made from a variety of fibers, such as polyester, rayon, cellulose (cotton and wood pulp), acrylic and other fibers, as well as some blends of fibers. The fabrics can be further modified to include antistatic and antimicrobial properties, etc. by incorporating suitable additive materials into the fiber or batts. One limitation of spunlaced nonwovens and nonwovens in general is durability over multiple washings. Therefore, spunlaced nonwovens were not acceptable for most uses in clothing and garments, with the exception of single-use garments such as medical gowns and limited-use protective garments.

Water interlacing produces an impressively strong fabric at a much lower cost than weaving and knitting. Unfortunately, the cycling of a typical washing machine wreaks havoc on the interlaced fibers and effectively destroys the fabric for its intended purpose as the fibers become unraveled. After a single wash, the fabric tends to have a noticeably worse appearance, such as pilling or a "worn" appearance, or may possibly be destroyed. Within a few washes, ordinary spunlaced nonwovens are almost always useless for their intended purpose. The fabric has an appearance as if it has been shredded.

In a process for providing durability in spunlaced nonwovens, DuPont addressed this problem by using a stitch pattern in which a thread is inserted into the fabric, forming a stitchbonded structure. The filament or staple yarns are "knitted" into the fabrics in a dense pattern and are quite resistant to cyclic tension or manipulation of the fabric. Therefore, the washed stitchbonded fabric does not suffer as much damage as seen in ordinary unreinforced spunlaced nonwovens. The stitchbonded structure has proven to be reasonably satisfactory in terms of performance for durable and reusable mattress covers, withstanding many hundreds of washings. However, there are aesthetic and cost considerations of the stitchbonded appearance that could make such a solution unattractive.

Others have attempted to produce a durable nonwoven fabric by adding binders to the fabrics. U.S. Patent 3,664,905 relates to a method of producing a batt suitable for use as a papermaker's felt comprising: superimposing a plurality of fiber packages such that substantially parallel fibers in one package extend in the cross direction to substantially parallel fibers in an adjacent package; needling the superimposed packages to form a layered batt; stretching the batt to stretch the fibers; applying an adhesive coating to at least one side of the batt; compressing the batt; and subjecting the batt to a jet of compressed air to break up coherent adhesive films into beads, whereby a portion of the adhesive adheres to the contact points and intersections of the fibers on the surface of the batt, and whereby the remaining beads are driven into the batt to adhere to the contact points of the individual fibers near the surface. U.S. Patent 4,623,575 relates to a strong, durable nonwoven fabric comprising polyester and/or polyolefin fibers arranged in a pattern of lightly interwoven, high density fiber regions. An adhesive bonding material is distributed over the fibers to impart improved strength properties to the finished fabric. The binders tend to make the resulting fabrics quite stiff. In fact, it appears that more binder is needed to make the fabrics durable than is needed to make them stiff. Clearly, stiffness is not a desirable quality for a number of uses, such as clothing and home furnishings. A second problem with binders is that they often extend to the surface, which has several undesirable consequences. The binders tend to be very hard after they have cured, and any place they extend through to the surface will be noticeable to the touch. It will feel like a pebble or similar texture, which is quite irritating. The second problem is that the binders often do not react to dyes and printing like the fibers in the fabric. As such, the binder becomes noticeable and unsightly.

It would clearly be highly desirable to be able to manufacture and use nonwovens that are durable enough to withstand numerous washings or similar abuse while exhibiting the qualities that can be obtained from spunlaced nonwovens.

SUMMARY OF THE INVENTION

It has now been determined that a durable fabric can be made by bonding two layers of fabric together to produce a composite construction with the feel and appearance of a conventional spunlaced nonwoven layer, but with significantly improved durability. The fabric may be a single layer or a composite.

A durable fabric can be made comprising: a first fabric layer comprising fibers; a second fabric layer comprising randomly aligned non-woven fibers; and a series of substantially discrete beads of the adhesive material securing the fibers in the first and second layers together such that the beads enclose a large portion of the periphery of some fibers that are at least one fiber thickness away from the first fabric.

In particular, the bonds enclose portions of fibers from both fabric layers without substantially penetrating to the outer surface of at least one of the fabric layers.

It is a further aspect of the present invention that a durable nonwoven fabric can be made comprising: a batt of randomly aligned nonwoven fibers; and a series of closely spaced individual beads of adhesive material meshed within the batt, a plurality of fibers being entrapped in each bead.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood by a detailed explanation of the invention which includes the drawings. Accordingly, drawings are included herein which are particularly suitable for explaining the invention; however, it should be understood that such drawings are for explanatory purposes only and need not be to scale. The drawings are briefly described as follows. In them:

Fig. 1 is a very good schematic arrangement of the manufacturing process for the manufacture of the material of the present invention;

Figure 2 is an enlarged partial perspective view of the calender rolls for making the composite of the present invention;

Fig. 3 is an enlarged partial plan view of the reinforcing insert used to create the bonds in the composite;

Fig. 4 is a partial perspective view similar to Fig. 2 showing a second arrangement for making the composite structure of the present invention; and

Figure 5 is a cross-sectional view of the composite of the present invention showing a single bond point.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to Figure 1 of the drawings, the plant for making the composites of the present invention is shown generally at 10. Figure 1 is a very good schematic drawing intended to express the general understanding of the plant and process while not overloading the drawing with detail.

The preferred method essentially comprises three generally separate steps shown in sequence in Figure 1. The first step is to produce two separate hydroentangled layers using first and second fabric manufacturing equipment shown generally at 20 and 30 in the upper and lower portions of the drawing. The method of producing hydroentangled layers is generally described in U.S. Patent No. 3,797,074 to Zafiroglu et al. and U.S. Patent No. 3,485,706 to Evans et al., and is incorporated herein by reference. Focusing on the second fabric manufacturing equipment 30, the method includes feeding a fiber package 32 to an airlaying device 35. The airlaying device 35 includes a toothed dispersion roll 36 which rotates at high speed relative to the feed speed of the package 32. The fiber is drawn out of the package 32 by the dispersion roller 36 and introduced into an air stream in the nozzle 37. The fiber is taken up on a compacting screen belt 41. The fiber on the belt 41, now generally referred to as a batt, is transported to a second belt 42 which is designed to carry of the batt under a series of high energy water jets, generally shown by the numeral 45. The high energy water jets intertwine the fibers to form a fabric. Typically, the fabrics are subjected to water intertwining from the underside by conveying them around a roller 49 to be struck by a second series of high energy water jets 50. The fabric is then dried by suitable equipment, such as steam heated rollers 54 and 55, to produce a stock fabric 59.

Both the first and second material lines 20 and 30 are essentially the same, producing the starting materials 29 and 59, respectively. It is preferred that the starting materials be received on a reel at the end of each line 20 and 30 so that the production rates of each line 20, 30 and the composite fabrication line 60 (described below) can be optimized, and that the lines can be operated independently for a maximum operating time.

Turning now to the process of combining the fabric layers together, a composite fabrication line is shown in the center of Figure 1 generally at 60. The stock fabric 59 is supplied to the composite fabrication line 60 and a mesh bonding layer 61 of thermoplastic mesh is supplied thereon from a feed roll 62. The mesh bonding layer 61 is illustrated in Figure 3 and comprises a very fine mesh-like material with dots 63 at the joints of the thermoplastic material. The fine strands 64 of thermoplastic material hold the mesh bonding layer together and effectively determine the spacing of the bonding points of the composite fabric 99 or mesh-like arrangement from one another. In the preferred embodiment, the dots 63 are less than one millimeter in diameter and are spaced approximately one (1) millimeter from adjacent dots 63. The fine strands 64 are quite small, being several microns thick. Such materials are used commercially in medical and automotive products by Smith and Nephew, Ltd. and Applied Extrusion Technologies as well as other sources.

The second source fabric 29 is placed on top of the mesh bond layer 61, thereby forming a layer assembly with the fabrics 29 and 59 on the top and bottom thereof. The layer assembly is then subjected to calendering between calender rolls 71 and 72 under controlled temperature, pressure and speed to melt the thermoplastic material in the mesh bond layer 61. Due to the surface tension of the molten thermoplastic material, the dots 63 of the mesh bond layer 61 form individual beads 65 (see Fig. 5) of the binder so that the fine connecting strands 64 between the dots 63 are separated and the material therein largely retracts into the beads 65. At the same time, the pressure of the calender rolls 71 and 72 forces a substantial portion of the fibers of the source materials into the beads so that the binder envelops or encloses a plurality of fibers in each source material at a specific location.

Partly with reference to Fig. 5, the structure of the composite can be more clearly understood. A dashed line 75 is provided to show the interface between the two layers of the precursor 29 and 59. Each precursor consists of a large number of individual Fibers 77. The fibers are randomly arranged in fabrics 29 and 59, however, it is generally known that the fibers in the batt preferably lie flat prior to hydroentangling. The fibers are described as having an XY orientation. After the fabric is hydroentangled, some of the fibers are forced through the fabric so that they have a Z component that extends up and down the fabric. The Z component fibers become entangled in and with the XY fibers, which continue to comprise a majority of the fibers, thereby forming the stable and strong hydroentangled fabric. As can be seen in Figure 5, some fibers 78 have a portion that extends in the Z direction even though the fiber is longer than the thickness of the fabric in the Z direction. Therefore, the fibers do not have to be completely vertical or Z oriented. It should also be seen that some of the Z-fibers 78 are also meshed or entrapped within the beads 65 of the binder. It is believed that this interaction of the Z-fibers 78 being captured and held by the beads 65 of the adhesive provides the greatest contribution to durability not possessed by water-entangled fabrics up to this point. However, the durability benefits may not be entirely due to the meshing of the fibers in the Z direction, but simply the meshing of so many fibers. Certainly it is believed that the meshing of the fibers in the Z direction in the beads produces the most durable fabrics, but it may be within the scope of the invention to simply have at least one nonwoven fabric having a plurality of closely spaced but discrete bonding points, the bonds comprising the meshing or entrapment of fibers within the nonwoven fabric.

Several other observations regarding the beads and fibers 77 and 78 that are worth discussing are that the bead 65 is present within the fabric and does not extend to the surface. Therefore, the surface of the composite retains the softness and appearance characteristics of the base fabric formed by the fibers 77. Second, the bead 65 preferably envelops or surrounds at least one half of the surface of the fibers 77 that are at least one fiber thickness away from the boundary between the two base fabrics. In the drawing and in the preferred embodiment, several fiber thicknesses of the fibers 77 from the boundary are enclosed in the beads 65 of the binder. This deeper fiber bond is a result of the considerable pressure applied by the calender rolls. The extent of entrapment of the fibers in the beads can also be described as the percentage of the thickness of each source material that is enclosed by the beads 65. For example, it is preferred that the beads not extend through 100% of the source material because that would mean that the adhesive would extend to the surface of the composite. However, 80 to 90% penetration may be quite acceptable. At the other end, it is preferred that about 10% or more of the source material be entrapped in the beads, although the scope of the invention is related to the amount that will make the composite durable.

Another observation is that it is also important that the bonds between adjacent beads are substantially broken or absent. The fabrics of the invention tend to exhibit rougher qualities after calendering and before washing. Once the fabric of the invention is washed, it expands in thickness after being tightly compressed, and it exhibits softness and drapability qualities comparable to conventional spunlaced nonwovens. If the beads were substantially bonded together, they would tend to make the composite more rigid. The individual bonding points do not provide a continuous film layer in the center of the fabric, but exist in individual beads that neither bond together nor penetrate to the surface of the fabric. The surface layers, while sufficiently water-interlaced to bond the filaments together and to maintain surface integrity and strength, are nevertheless sufficiently free to provide a soft, drapable, resilient material, particularly after washing or mechanical action.

It must be noted that the two starting materials may be the same or quite different. The starting materials may differ in terms of mass per unit area or fiber composition, construction or a combination of differences. The potential binders for the base layers of the fabric may be polyethylene, polyamide, polyester, polypropylene and polyvinyl alcohol as well as other potential adhesives. It is preferred that the adhesives be in a thermoplastic state so that the beads can be controlled as they are compressed by calender rolls or other arrangement for compressing the starting materials.

While it is preferred that the binder be applied in the form of a mesh bond layer 61, it has been found that it can be applied directly to the underlying base fabric. Referring to Figure 4, a simple series of adhesive applicators 80 are shown which apply a small amount of the binder to the fabric 59. The small amount of binder is referred to as droplets and forms bead bonds in a manner similar to the dots of the mesh bond layer 61. The arrangement of the droplets may not be as evenly distributed as the dots in a mesh; it is believed that the distribution may be close enough to provide a satisfactory coating while maintaining individual bond points or positions to provide the other desirable properties.

The size of the beads is preferably selected or defined so that the adhesive will enclose the fibers of both fabric layers, but will not "bleed through" to both surfaces of the durable fabric. The term beads is used to describe the adhesive material in the fabric, which is likely not spherical. In fact, the beads are quite amorphous, generally being flatter and wider due to nip pressure. It is noted that in some applications where one side of the fabric may be concealed or shielded, the adhesive may extend to the surface of that side. It is noted, however, that one of the qualities of the fabric of the invention is that the adhesive is not at all perceptible on the surface of either side. Therefore, the upper limit of the size of the beads is likely to be limited by the thickness of the fabric, and the lower limit is related to the ability to cause the adhesive to enclose the fibers in each fabric layer. In most cases the beads will be less than 2 millimeters in diameter and often less than one millimeter.

Another consideration for the dots or beads is the spacing. It is believed that the best results are achieved when the beads are placed close together. However, it is recognized that a suitable composite with greater durability than normal nonwovens can be made if the beads are spaced considerably further apart than is preferred. For example, it may be appropriate to space the beads so that there is a spacing of four to five millimeters between the beads, and perhaps a larger spacing is possible. However, such spacing may indicate or require large beads which will penetrate substantially through the thickness of the fabric. Therefore, in such circumstances the fabric layers may be quite thick, or the adhesive may extend to the surface. In the preferred arrangement the spacing is about 2 millimeters or less, and more preferably about one millimeter or less.

Activation of the adhesive requires a balance of several considerations. For example, the speed at which the fabrics can pass through the nip will depend on the melting temperature of the adhesive, the temperature of the heated roller and the pressure in the nip. Other factors can affect the bond, which include the hardness of the pressure roller, the diameter of the rollers. The adhesive in the dots or beads is preferentially activated by the heated roller, regardless of how the dots are applied to the fabrics.

Another option in the system to perhaps speed up the manufacturing process would be to preheat one or both of the fabrics so that the calender rolls do not have to heat the fabric from ambient temperature. The calender rolls 71 and 72 are arranged so that the lower roll is heated by hot oil or other heat source and the upper roll 71 applies downward pressure to the heated roll 72. It is therefore preferred that the upper feedstock 29 be heated which is farthest from the heated roll. However, the preheaters may be arranged in a variety of potential locations as shown by the numerals 82, 83, 84 and 85 or in any combination found acceptable. It was found that preheating the mesh bond layer 61 was not satisfactory at all as it tends to melt unevenly and without the two materials holding the dots in place, sections without the beads or bonds could be left.

It should also be noted that water entanglement is not the only nonwoven technology that would benefit from the present invention. Needle-punched fabrics, in which the Z-fiber direction is arranged by a mechanical needle driven into a batt of randomly oriented fibers, also work well within the scope of the present invention.

It should also be noted that in some cases it may be desirable in accordance with the present invention to bond a nonwoven, woven or knitted fabric or a material made in accordance with a technology other than spunlacing or needle felting technology. For example, it may be desired to have a lightweight knitted fabric in conjunction with an inexpensive, heavier spunlaced nonwoven as a backing layer for thickness or softness. By securing the woven fabric to the nonwoven such that individual beads of adhesive encase sufficient portions of the fibers of the spunlaced or needle felted nonwoven, the resulting fabric will be durable through multiple launderings.

The following is a more detailed description of a sample of the fabric of the invention: A layer of the fusible thermoplastic batt or mesh, such as Delnet® fusible polyethylene batt (weight range of 0.2 to 1.0 oz/yd² or 6.8 to 33.9 g/m², with a preferred range of 0.3 to 0.5 oz/yd² or 10.2 to 17.0 g/m²), is placed between two layers of the spunlaced nonwoven fabric. The fabric layers should be at least 0.6 oz/yd² (20.3 g/m²) up to about 5 oz/yd² (170 g/m²) for the fabric contacting the heated roller, or up to 8 oz/yd² (271 g/m²) for the non-"preheated" fabric. The preferred range is about 0.9 to 4.0 oz/yd² (30.5 to 136 g/m²). The two fabric layers can be made of cellulosic material such as rayon or lyocell, or thermoplastics such as polyester or polyamide, or blends if desired to produce a specific set of properties. A preferred blend was lyocell and Microsafe(TM) acetate, which provides a durable antimicrobial absorbent comfort layer.

The adhesive mesh layer may have a sufficiently lower melting point than the surface layers to allow reasonable process rates at a temperature that will not damage the surface layers. It may be, but is not limited to, a condensation polymer or copolymer such as polyamides or polyesters, or an addition polymer such as polyethylene or vinyl copolymers. The reinforcing ply and surface layer polymers may be selected for reasonable surface energy compatibility to ensure proper adhesion, but good physical entanglement is not required. It is conceivable that the beads of the present invention could be formed using a pierced or apertured film which, upon application of heat, would cause the formation of individual bonding points. There are likely other methods that could be used to form the beads.

The surface fabrics are preferably needled, such as by water entanglement or needle felting, to impart a significant degree of "Z" directionality to the fabrics so that many of the fibers in the layer are present on both surfaces and their attachment to the inner surface of the layer with the reinforcing ply polymer provides stability to the outer surface. Other batt manufacturing facilities for nonwoven fabrics result in almost all of the fibers being in the plane of the fabric and unavailable to hold the outer surface to the inner surface.

Bonding is preferably accomplished by using a heated pressure calender. The preferred temperature range is from 300 degrees F (149 degrees C) to allow reasonable process speed, up to about 450 degrees F (232 degrees C) for thermoplastics such as polyester, up to about 550 degrees F (288 degrees C) for cellulosic materials. The pressures should be sufficient to extrude the molten reinforcing ply polymer into the surface layers to an extent that will encapsulate a reasonable number of fibers, but will not precipitate on the surface.

A number of samples were prepared and subsequently characterized in Tables I to VIII. The fabric samples were prepared essentially as described below.

EXAMPLE 1

Example 1 has two layers of the 70% lyocell and 30% acetate hydroentangled spunlaced nonwoven fabric with a nominal weight per unit area of 68 g/m² (2.0 oz/yd²) bonded to a 17 g/m² (0.51 oz/yd²) mesh product having small bonded polyethylene dots. The product is available from Applied Extrusion Technologies of Middletown, DE as X530 batt. The adhesive is cured by a heated calender roll. The fabric is passed through a nip at 6.4 m/min. (7 ypm) with a pressure of 165 lbs. per linear in. (pli) with the heated roll at 211ºC (411ºF) and the pressure roll having a durometer of 90 on a Shore 80 scale. The pressure roller showed a diameter of 12 in., and the heated roller showed a diameter of 9.75 in.

EXAMPLE 2

Example 2 comprises two layers of the 100% Lyocell water-interwoven spunlaced nonwoven fabric having a nominal weight per unit area of 78 g/m² (2.3 oz/yd²) and bonded to a 17 g/m² polyethylene mesh as described in Example 1. The adhesive is cured by a heated calender roll. The adhesive was cured by the same equipment and under the same conditions as in Example 1, but at 209ºC (409ºF) and at a pressure of 132 pli.

EXAMPLE 3

Example 3 comprises two layers of the 100% Lyocell water-interwoven spunlaced nonwoven fabric having a nominal weight per unit area of 32 g/m² (0.95 oz/yd²) and bonded to a 17 g/m² polyethylene mesh as described in Example 1. The adhesive is cured by a heated calender roll. The adhesive was cured by the same equipment and under the same conditions as in Example 2, but at 21.5 m/min. (23.5 ypm) and at 218ºC (424ºF).

EXAMPLE 4

Example 4 has two layers of the water-interwoven spunlaced nonwoven fabric, one layer being 100% lyocell with a nominal weight per unit area of 78 g/m² (2.3 oz/yd²) and the second layer being 100% polyester with a nominal weight per unit area of 68 g/m² (2.0 oz/yd²). The bonding therebetween is accomplished by depositing small beads of the polyamide adhesive with metered jets at close intervals. The adhesive is cured by a heated calender roll. The adhesive was cured by the same equipment and under the same conditions as in Example 2, but at 6.4 m/min. (7 ypm) and at 172ºC (342ºF).

EXAMPLE 5

Example 5 has two layers of the water-interwoven spunlaced nonwoven fabric, one layer being 100% lyocell with a nominal weight per unit area of 32 g/m² (0.95 oz/yd²) and the second layer being 100% polyester with a nominal weight per unit area of 34 g/m² (1.0 oz/yd²). The bond therebetween is achieved by depositing small beads of the polyamide adhesive with metered jets at close intervals. The adhesive is pressed through a heated calender roll The adhesive was cured using the same equipment and under the same conditions as in Example 2, but at 12.8 m/min. (14 ypm).

EXAMPLE 6

Example 6 has two layers of the 100% Lyocell water-interwoven spunlaced nonwoven fabric, each with a nominal mass per unit area of 78 g/m² (2.3 oz/yd²). The bond between them is achieved by depositing small beads of the polyamide adhesive in metered jets at closely spaced intervals. The adhesive is cured by a heated calender roll. The adhesive was cured by the same equipment and under the same conditions as Example 2, but at 12.8 m/min. (14 ypm) and at 169ºC (336ºF).

EXAMPLE 7

Example 7 has a first layer of the 100% lyocell hydroentangled spunlaced nonwoven fabric with a nominal weight per unit area of 78 g/m² (2.3 oz/yd²) and a second layer of the 100% polyester hydroentangled spunlaced nonwoven fabric with a nominal weight per unit area of 34 g/m² (1.0 oz/yd²). The bond between the layers is achieved by depositing small beads of the polyamide adhesive with metered jets at close intervals. The adhesive is cured by a heated calender roll. The adhesive was cured by the same equipment and under the same conditions as Example 2, but at 9.1 m/min. (10 ypm) and at 172ºC (342ºF).

EXAMPLE 8

Example 8 has two layers of the 100% polyester water-interwoven spunlaced nonwoven fabric, each having a nominal weight per unit area of 34 g/m² (1.0 oz/yd²). The bond between the layers is achieved by depositing small beads of the polyamide adhesive onto a layer at closely spaced intervals using metered jets. The adhesive is cured by a heated calender roll. The adhesive was cured by the same equipment and under the same conditions as Example 2, but at 12.8 m/min. (14 ypm) and at 169ºC (336ºF).

DESCRIPTION OF THE TEST METHODS USED

The measurements of mass per unit area, thickness and tensile measurements (fabric tear strength after grab test and elongation) are based on the measurement methods according to ASTM D1117.

The wet fabric tensile strength after grab test and elongation are the same as previous, except that the fabric is moistened before measurement.

The absorbency and rate of absorption are measured using a Gravimetric Absorbency Tester (GATS) available from M&K Systems with the fabric under a load of approximately 350 kg/m2. Essentially, the GATS measures the amount of liquid and the rate at which it is absorbed through an outlet in the system. The time T50 is the time it takes for the fabric to absorb half of its total water absorption. The rate at T50 is the slope of the absorption curve at time T50.

The intrinsic absorptivity is a measurement of the amount of water that the material will absorb as a percentage of the mass of the material. Material samples are completely immersed in water and allowed to drip for approximately one minute. The difference in the mass of the sample in the dry and in the The mass of the sample in the wet state is divided by the mass of the sample in the dry state and then multiplied by 100 so that it can be expressed as a percentage.

The suction speed is measured according to the INDA STM 10.1 method.

Handleometer measurements are taken on a machine made by the Thwing-Albert Instrument Co. of Philadelphia. The measurements are the force in grams to push a 100 mm wide fabric into a slot that is 100 mm wide. This is a quantitative measure of drapability. The Handleometer data includes data from both the top and bottom of the fabrics.

In all tables below, the numbers collected are based on multiple experiments. Therefore, the data are presented as the mean and standard deviation with a slash in between. Therefore, the representation is: mean/standard deviation. TABLE I TABLE II TABLE III TABLE IV TABLE V TABLE VI TABLE VII TABLE VIII

For comparison purposes, handleometer tests were conducted on a single layer of fabric used in Examples 1 and 2. Side-by-side plots of data are presented in Table VI to show the comparison. It should be noted that all data presented in Table IX are normalized for mass per unit area. TABLE IX

Clearly, the fabrics of the invention exhibit exceptionally comparable drapability to the underlying normal spunlaced nonwoven fabrics with the notable exception that one would very unlikely be able to compare a single ply fabric after three washes as there would be little left that would be recognizable as a fabric.

There are other applications of the present technology. For example, examples of composites having different fibers on one side versus the other are shown above. This is to demonstrate that different starting materials can be used in the invention. The particular materials can be tailored to have very different properties that are compatible for a particular use. In an envisaged use, the composite may be absorbent (hydrophilic) on one side while providing a barrier to liquids (hydrophobic) on the other side. A composite with such qualities may have particular utility in the field of medical gowns and drapes or perhaps as protective clothing. Other possible combinations of the starting materials having different, contrasting or similar properties should be conceivable on the basis of the foregoing disclosure.

Another application of the present invention is to make a fabric with a base layer that exhibits durability. Although the base layer will clearly have an adhesive on one surface of the fabric, it will exhibit durability due to the small, closely spaced individual dots of adhesive that bind the fibers together and do not allow the fibers to unravel in a washing machine as normal spunlaced nonwovens. The process for making a fabric from one layer would be essentially the same as making a composite fabric without the second layer. Perhaps a release paper or other film-like material could be placed on the back of the fabric that would be peeled off after the beads were formed and cured. Alternatively, the pressure roller could be provided with a release coating in the nip to prevent adhesive from accumulating on it.

The foregoing specification and drawings were intended to explain and describe the invention in order to contribute to the general basis of knowledge. In consideration for this contribution to knowledge and understanding, exclusive rights are sought and must be respected. The scope of such exclusive rights is not to be restricted or limited in any way by the specific details and preferred arrangements which may have been shown. Clearly, the scope of any patent rights granted on this application should be estimated and defined by the claims which follow.

Claims (28)

1. A durable nonwoven fabric comprising: a batt of randomly aligned nonwoven fibers; and a series of closely spaced individual beads of adhesive material meshed within the batt, a plurality of fibers being entrapped in each bead. 2. The fabric of claim 1, wherein the fabric is a spunlaced nonwoven fabric. 3. The fabric of claim 2, wherein the spunlaced nonwoven fabric is a water-entangled spunlaced nonwoven fabric. 4. The fabric of claim 2, wherein the spunlaced nonwoven fabric is a needle-felted spunlaced nonwoven fabric. 5. Durable fabric that features: a first fabric layer comprising fibers; a second fabric layer comprising randomly aligned non-woven fibers; and a series of substantially discrete beads of adhesive material securing the fibers in the first and second layers together such that the beads enclose a large portion of the periphery of some fibers which are at least one fiber thickness away from the first fabric. 6. The durable fabric of claim 5, wherein the second fabric layer is a hydroentangled spunlaced nonwoven fabric. 7. The durable fabric of claim 5, wherein the second fabric layer comprises: fibers, wherein at least some of the fibers exhibit an orientation in the Z direction in the fabric; and a series of substantially discrete beads of the adhesive material securing the fibers in the first and second layers together such that some fibers in the Z direction in the second fabric layer have portions substantially surrounded by the adhesive in some of the beads. 8. A durable fabric layer according to claim 7, wherein the fibers extend in the Z-direction substantially through the thickness of the fabric. 9. The durable fabric layer of claim 7, wherein the first fabric layer comprises fibers having a Z-direction orientation extending substantially through the thickness of the fabric. 10. The durable fabric layer of claim 7, wherein the beads comprise thermoplastic polymer. 11. The durable fabric layer of claim 7, wherein the beads include fibers positioned away from the boundary between the first and second fabrics by at least one other fiber in the same fabric layer. 12. A durable fabric layer according to claim 7, wherein the beads have a diameter of less than 2 mm. 13. A durable fabric layer according to claim 12, wherein the beads are spaced from an adjacent bead by less than 4 mm. 14. The durable fabric layer of claim 7, wherein the first fabric layer is a woven fabric layer. 15. The durable fabric layer of claim 7, wherein the first fabric layer is a knitted fabric layer. 16. The durable fabric sheet of claim 7, wherein the second fabric layer is a hydroentangled nonwoven fabric sheet. 17. The durable fabric sheet of claim 16, wherein the first fabric layer is a hydroentangled nonwoven fabric sheet. 18. The durable fabric layer of claim 17, wherein at least one fabric comprises polyester and the adhesive is a thermoplastic polymer. 19. A process for producing a durable fabric comprising the steps of: Providing a batt of randomly aligned non-woven fibers; Positioning adhesive material on the fiber web; and Activating the adhesive material to form closely spaced individual beads of the adhesive material within the batt, enclosing a plurality of fibers within each bead. 20. The method of claim 19, wherein the step of activating comprises running the batt with the adhesive material through a heated nip. 21. A process for producing a durable fabric comprising the steps of: Providing a first layer of the fabric comprising fibers; Providing a second layer of the nonwoven fabric having randomly aligned fibers; Positioning adhesive material on one of the first or second layers; laying one layer of the fabric over the other to form a layered assembly with the adhesive material between the first and second layers; and Activating the adhesive material to form closely spaced individual beads enclosing a plurality of fibers from each layer within each bead. 22. The method of claim 21, comprising the following steps: providing the second layer of the fabric comprising fibers, at least a portion of the fibers having a Z-component orientation; Positioning adhesive material on one of the first or second layers; laying one layer of the fabric over the other to form a layered assembly with the adhesive material between the first and second layers; and Activating the adhesive material to form individual beads that entrap fibers in each of the layers together such that portions of the Z-component fibers are substantially surrounded by some of the beads. 23. The method of claim 22, wherein the step of activating the adhesive material comprises heating. 24. The method of claim 22, wherein the step of activating further comprises pressing the fabric layers together while heating the adhesive material. 25. The method of claim 22, wherein the step of positioning adhesive material comprises laying a mesh having interconnected adhesive dots with fine sections connecting the dots into a mesh. 26. The method of claim 22, wherein the step of positioning adhesive material comprises depositing small drops of adhesive material onto a layer. 27. The method of claim 22, wherein the step of activating the adhesive material comprises passing the layered assembly through a heated calender to heat and compress the fabric layers together in the melting adhesive material. 28. The method of claim 27, further comprising preheating one of the fabric layers prior to the heated calender.